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@Jarlaxle I wanna be clear your submission is NOT being rejected. I don't reject concepts unless they are done in bad faith, are badly misinterpreted from the ancestor, or utterly broken to the point of no amount of tweaking could fix. For this post, it seems to just be down to the joint issue and right before it was bumped here you and Colddigger seemed like you might be hitting on a solution. There were no personal reasons or anything for why it was bumped, simply just that the policy is after we hit less than 30 pending submission and post still being actively worked on has one week to finish or be bumped to the next gen. We hit that point last Tuesday so this post should have been warned but wasn't because the announcement went up on the discord and I apologies for that.

To me putting something in the graveyard is at most just putting it on hold until its ready for next/a later generation or abandoned, but I'm noticing the connotations are pretty skewed towards it being interpreted as a outright permanent rejection. I'm going to change the name of this subforum to a less charged term

QUOTE (MNIDJM @ Feb 3 2023, 01:11 AM)

@Jarlaxle I wanna be clear your submission is NOT being rejected. I don't reject concepts unless they are done in bad faith, are badly misinterpreted from the ancestor, or utterly broken to the point of no amount of tweaking could fix. For this post, it seems to just be down to the joint issue and right before it was bumped here you and Colddigger seemed like you might be hitting on a solution. There were no personal reasons or anything for why it was bumped, simply just that the policy is after we hit less than 30 pending submission and post still being actively worked on has one week to finish or be bumped to the next gen. We hit that point last Tuesday so this post should have been warned but wasn't because the announcement went up on the discord and I apologies for that. To me putting something in the graveyard is at most just putting it on hold until its ready for next/a later generation or abandoned, but I'm noticing the connotations are pretty skewed towards it being interpreted as a outright permanent rejection. I'm going to change the name of this subforum to a less charged term

What if a gen 166 spot was left open for the visorbill through delaying another one of mine?

The visorbills migration patterns should have evolved along with the changing of the continents and island chains, it was meant for a radiation that could evolve locally in different ways on all the different islands, and - perhaps not so successfully - their description was meant to read like a mechanical instruction manual, an "how to make your own visorbill" guide so that anyone could.

In contrast, the Ophan Skeggox inhabit the main continent, their evolutionary story was less impacted by the geographic and climate changes between the weeks, and their current lifestyle isn't under a lot of evolutionary pressure.

Could I delay the Skeggox to gen 167 to keep the gen 166 spot open for the visorbill while we contiue to brainstorm the joint design?

If the discussion is gonna continue for another 12 pages it isn't worth it. We need to finish the generation and get the next one opened for the newbies.

Alternatively, @MNIDJM Just... Talk to your colleagues .

If they tell you that historically wrists and ankles have evolved to be less or more flexible in lineages depending on circumstances and change to their lifestyle (like our own have evolving from ground dwelling to arboreal and back again), then the existing version of the lineage should have being viable. Once that's established, should it really matter how many pages someone will insist that ankles can't gain flexibility? If Coolsteph is true to correct me and its indeed not political, then it shouldn’t matter anymore than anyone else trying to argue ad infinitum to break the deadline limit - not for the next 12 pages or the 12 previous ones - which would mean the visorblls met the criteria within your deadline. I'd say it met it within the OP, but even if you want to say the novel anatomy required more than the usual, well, what about by the time the first version of the CAD animation was introduced, or the 2nd? I'm not aware of any other submission that required more than that (or that required that in the first place).

If they say ankles can't and haven't evolve flexibility over time - bonus points if they type the answer while turning their forelimbs over a keyboard - that would be fascinating too, could be very informative of the discussion even if it is for gen 167.

This post has been edited by Jarlaxle: Feb 2 2023, 08:55 PM

To clarify, the way that saucebacks use their Albert joint is why they can't just evolve to bend sideways out of nowhere. As obligate bipeds which have been digitigrade and cursorial for hundreds of millions of years, their Albert joints, if they could ever bend side to side at all, would have lost that ability long ago to keep them stable while running for the same reason that knees do not typically bend side to side, with all adjustments happening at the toes instead. Bird legs also work this way and have relatively similar musculature lacking anything to move their "ankles" (which, similarly, are not actually true ankles) side to side. A bird's heel, and a sauceback's Albert joint, can therefore be considered analogous as far as evolving new flexibility goes.

In both cases, the sudden transformation of the joint into a saddle would cause the creature, bird or sauceback, to fall over because the muscles to adjust for the side-side wobble do not exist. If the muscles appeared out of nowhere beforehand, it would restrict the creature's ability to use the joint effectively. The chances of both appearing at the same time in the same individual are so low that I'd consider them practically impossible. You're not gonna get any side to side flexibility in the joint unless you dramatically change how your organism moves to no longer be affected by either problem, which I find to be a very unlikely path for this lineage, which is paralleling the evolution of perching birds. Maybe if they take a detour through sprawling as an aquatic adaptation, they might be able to get there.

You'd need to come up with a new perching mechanism though, as the tendon-based method birds use only works because the heel is a hinge joint.

Saucebacks have this bone you might be able to use as a furcula

QUOTE

it forms a unique structure called the triosseal canal, which houses **a strong tendon** that connects the supracoracoideus muscles to the humerus. This system is responsible for lifting the wings during the recovery stroke. ... As the thorax is compressed by the flight muscles during downstroke, the upper ends of the furcula spread apart, expanding by as much as 50% of its resting width, and then contracts.  ..in addition to strengthening the thorax, the furcula **acts like a spring** in the pectoral girdle during flight. It expands when the wings are pulled downward and snaps back as they are raised. In this action, the furcula is able to store some of the energy generated by contraction in the breast muscles, expanding the shoulders laterally, and then releasing the energy during upstroke as the furcula snaps back to the normal position.

It's no crank rocker...

It’s used for pumping the lungs…. HOWEVER if the Visorbill uses Ram ventilation (air is forced into the lungs via forward movement)

Imo but it might just work then.

@HethrJarrod





That is one possible anchor point, and possibly the musculature in that area is a good option because of its proximity to the limb membrane which the fascia or chord or what have you would be in association with.


Looking at that now I'm kind of curious how the bone exactly functions for breathing, if it acts as a standstill support for muscles that pump lungs, or if the bone itself is mobile for helping to pump lungs.

If the idea was to use it as an anchor point for something, I would be interested in knowing what muscles you were wanting to associate, and if it was mobile during its use of breathing, I would wonder if it were to constrict the airways during flight if used the way that you're suggesting...

But if it were to be moving, mobile, the bone itself being used to help in ventilating the lungs, then that has implications for what sauce backs actually look like. It would suggest that they actually have a tail has a pumping motion visible comparable to an insect abdomen during breathing.


Given the through tube design of the respiratory system of these, and even their cousins which independently developed a through breathing ventilation, the ram ventilation concept strikes me as very applicable. At the very least, a hybridization of it and active breathing.



Membrane reference on their cousin



Musculature of their cousin



Musculature overlay with visible skeleton of their cousin.


While HethrJarrod is offering her idea I'll offer a better visual of my own previously dabbled bone concept.



The foot bone, there's only one foot bone, is shrunk so that the base of the wing toe is in comparably close proximity to the Albert joint and sidesteps the need to adjust anything else. While the first segment of the wing toe elongates to replace that length loss, and the second segment of the wing toe acts as I guess the final Wing segment functionally?

The saddle joint between the first and second segments of the wing toe May need more reinforcements so that it is strong enough to be that portion of a wing, but could also be unnecessary, and could even be changed into a hinge joint if that makes it simpler, I personally don't think it needs to be.

One thing about my design is that because the foot bone is short, it makes me wonder if that means the muscle used to extend the wing toe would lose strength potential. I think that the muscle could probably be extended in some manner, either down along the first segment of the wing toe (though I question the safety of the muscle being across a saddle joint like that) or possibly Make the foot bone nice and wide so that the muscle form becomes convergent rather than fusiform.



Is also was suggested to me that the small bone above the foot bone is supposed to be fitted, which is interesting to consider because that means that possibly the point in the skeleton that everyone has been talking about are different points in the skeleton.




Here is the skeleton that I had been initially working with, if curious. There is some notable skeletal differences between the two.


If it's a fitted joint, well first I'm curious why it wasn't fused, but that's beside the point, it as a fitted joint may not really have muscles directly associated with it. Rather it may have muscle or tendon that spans across it, while the joint itself if it were to become more mobile may result in a limb that tends to kick out at that point initially, though with a long toe for standing on that doesn't seem like a real big problem. Just adjust where your toe is standing. Kind of like having bowed legs.

"Retinaculum" is something important here when considering how to maintain the shape of the limb, as that is what keeps tendons arrange the way that they need to be along the bone.

Alternatively, it may be able to be manipulated indirectly by muscles spanning across it as they tug on the bones adjacent to it if it were to be loose. I don't know how safe that is, but honestly I could injure myself if I were to contract my muscles as far as I could and something that has this kind of system probably would just not contract their muscles any further than the joint would allow for. Hopefully that would not compromise other parts, but I suspect that there ought to be a position where they do in fact lock in order to allow maximum strength application of a muscle, probably the one associated with extending the wing toe since that is likely going to be the position that requires the most power application, or strength application.

This post has been edited by colddigger: Feb 3 2023, 09:43 AM

I could be misinterpreting this, but it looks like ostriches manage the differences between two muscle set along the inner ankle (TCf & TCt) to stabilize it, as their simulated exertion stays consistent regardless of running phase. Given the comparison to a birds elbow of a wing, looking at hawk wing muscles they seem similarly have opposing muscle sets that are able to do the same thing, such as the BR muscle and SU. Alternatively, given the horse like hock shape of the albert bone, it should need a deep digital flexor.
The reason I knew to look for those is simply that bird joints don't form mechanical locks - meaning if they weren't opposing side to side forces they'd wobble until the tendons are in maximum stretch, if not outright flailing. It doesn't matter which critter you compare it too, there has to be something, not having any forces that can provide lateral balance just doesn't make mechanical sense, even if the skeleton worked in a simulated vacuum, and it doesn't, they have to be able to counter outside forces. What would happen if one side was impacted by a force the other side wasn't, like let's say, air resistance? There have to be variable lateral forces.
As for the extreme coincidence of them growing in the same time as an increased range of motion, that’s just as coincidental as the fact we build up the very same muscles we use, that's how gyms take our moneyz.

@HethrJarrod - I have not thought about that at all but I absolutely love the idea.
While I haven't thought of it in terms of ram ventilation, the visorbill's intake spiracles do face forward during flight. It might not contradict the bone's use for respiration though. Maybe it could even allow future visoriblls to use their locomotion as part of their breathing, even for future flightless ones that don't experience ram pressure.
it is a bit of distance for the muscle connection area to travel too in one generation, but it's a potential for the next generation. I did have a very vague notion that the 3 ways to get rid of the grashof's muscles drag are to place in front of the chest, flatten it under the belly or placed it towards the back, and that future generations should branch into all 3 routes. Your idea fits brilliantly for the 3rd one.
One thing I am not sure of is at what point did that bone consolidate into one lung bone, because biats still had 4 lung pairs when the songsuace evolved, so I guess it depends on what happened first? If the biat didn't have that consolidated lung bone I will have to think about how that might have evolved differently in the songsuace set up, though I can easily imagine a similar two bone system, which should still allow your idea.

@colddigger, while I still don't think its necessary for evolving the grashof muscle, your idea does compensates for a major weaknesses in the grashof muscle design, and that is the dependency on built up momentum.
Where you would need sturdy local muscles to exert control over the spin, for instance if you wanted to use the spinning for something that can break the trajectory of the motion, let's say wood pecking by using the grashof muscle to swing the torso and drill into wood, or digging, the hard surface would break the trajectory for the visorbill forcing it to build up momentum again, but with your idea they'd have the local foot muscles to push through. It's also a plausible pathway for quadruped saucebacks, as well as reducing the weight at the wings.

Side note: while looking this up I found a beautiful anatomy rabbithole called "What's in john's freezer" https://whatsinjohnsfreezer.com/ that anyone who's interested in anatomy and doesn't mind a bit of dinner-quality gore should go to, I can't stop reading it. He even goes into a bit of spec evo like analyzing star wars alien anatomy. Highly recommended for all spec evo anatomy enthusiast.

This post has been edited by Jarlaxle: Feb 3 2023, 05:18 PM

QUOTE (Jarlaxle @ Feb 3 2023, 06:57 PM)

I could be misinterpreting this, but it looks like ostriches manage the differences between two muscle set along the inner ankle (TCf &  TCt) to stabilize it, as their simulated exertion stays consistent regardless of running phase. Given the comparison to a birds elbow of a wing, looking at hawk wing muscles they seem similarly have opposing muscle sets that are able to do the same thing, such as the BR muscle and SU. Alternatively, given the horse like hock shape of the albert bone, it should need a deep digital flexor.  The reason I knew to look for those is simply that bird joints don't form mechanical locks - meaning if they weren't opposing side to side forces they'd wobble until the tendons are in maximum stretch, if not outright flailing. It doesn't matter which critter you compare it too, there has to be something, not having any forces that can provide lateral balance just doesn't make mechanical sense, even if the skeleton worked in a simulated vacuum, and it doesn't, they have to be able to counter outside forces. What would happen if one side was impacted by a force the other side wasn't, like let's say, air resistance? There have to be variable lateral forces. As for the extreme coincidence of them growing in the same time as an increased range of motion, that’s just as coincidental as the fact we build up the very same muscles we use, that's how gyms take our moneyz.

Mechanical locks like flanges that physically restrict the joint from bending any other way, which is what makes it a hinge joint by definition? Are we even looking at the same bones? They don't need muscles to constantly adjust precisely because they literally do have mechanical locks! And so do sauceback bones!

And ostriches don't even have any muscles below the ankle!

Point to me where there is a muscle in a bird heel that does that work that can be done by the bone flanges that they literally have with far less energy.

QUOTE (Disgustedorite @ Feb 4 2023, 01:37 AM)

QUOTE (Jarlaxle @ Feb 3 2023, 06:57 PM) I could be misinterpreting this, but it looks like ostriches manage the differences between two muscle set along the inner ankle (TCf &  TCt) to stabilize it, as their simulated exertion stays consistent regardless of running phase. Given the comparison to a birds elbow of a wing, looking at hawk wing muscles they seem similarly have opposing muscle sets that are able to do the same thing, such as the BR muscle and SU. Alternatively, given the horse like hock shape of the albert bone, it should need a deep digital flexor.  The reason I knew to look for those is simply that bird joints don't form mechanical locks - meaning if they weren't opposing side to side forces they'd wobble until the tendons are in maximum stretch, if not outright flailing. It doesn't matter which critter you compare it too, there has to be something, not having any forces that can provide lateral balance just doesn't make mechanical sense, even if the skeleton worked in a simulated vacuum, and it doesn't, they have to be able to counter outside forces. What would happen if one side was impacted by a force the other side wasn't, like let's say, air resistance? There have to be variable lateral forces. As for the extreme coincidence of them growing in the same time as an increased range of motion, that’s just as coincidental as the fact we build up the very same muscles we use, that's how gyms take our moneyz. Mechanical locks like flanges that physically restrict the joint from bending any other way, which is what makes it a hinge joint by definition? Are we even looking at the same bones? They don't need muscles to constantly adjust precisely because they literally do have mechanical locks! And so do sauceback bones! And ostriches don't even have any muscles below the ankle! Point to me where there is a muscle in a bird heel that does that work that can be done by the bone flanges that they literally have with far less energy.

The tibialis cranialis caput tibiale (TCT) & the tibialis cranialis caput femorale (TCF) are located on the shin bone but pull tandons that extend to two sides of the inner ankle allowing them to create lateral balance. The sides of a hinge joints provide support but don't form a lock, on their own the curves would still allow a range of motion that the muscles and tendons would need to restrain, not to mention the need to provide variable lateral support on their own when it comes to resisting outside forces, which would be needed for anything that adapted its limbs to fly inside an atmosphere.

QUOTE (Jarlaxle @ Feb 3 2023, 08:06 PM)

QUOTE (Disgustedorite @ Feb 4 2023, 01:37 AM) QUOTE (Jarlaxle @ Feb 3 2023, 06:57 PM) I could be misinterpreting this, but it looks like ostriches manage the differences between two muscle set along the inner ankle (TCf &  TCt) to stabilize it, as their simulated exertion stays consistent regardless of running phase. Given the comparison to a birds elbow of a wing, looking at hawk wing muscles they seem similarly have opposing muscle sets that are able to do the same thing, such as the BR muscle and SU. Alternatively, given the horse like hock shape of the albert bone, it should need a deep digital flexor.  The reason I knew to look for those is simply that bird joints don't form mechanical locks - meaning if they weren't opposing side to side forces they'd wobble until the tendons are in maximum stretch, if not outright flailing. It doesn't matter which critter you compare it too, there has to be something, not having any forces that can provide lateral balance just doesn't make mechanical sense, even if the skeleton worked in a simulated vacuum, and it doesn't, they have to be able to counter outside forces. What would happen if one side was impacted by a force the other side wasn't, like let's say, air resistance? There have to be variable lateral forces. As for the extreme coincidence of them growing in the same time as an increased range of motion, that’s just as coincidental as the fact we build up the very same muscles we use, that's how gyms take our moneyz. Mechanical locks like flanges that physically restrict the joint from bending any other way, which is what makes it a hinge joint by definition? Are we even looking at the same bones? They don't need muscles to constantly adjust precisely because they literally do have mechanical locks! And so do sauceback bones! And ostriches don't even have any muscles below the ankle! Point to me where there is a muscle in a bird heel that does that work that can be done by the bone flanges that they literally have with far less energy. The tibialis cranialis caput tibiale (TCT) & the tibialis cranialis caput femorale (TCF) are located on the shin bone but pull tandons that extend to two sides of the inner ankle allowing them to create lateral balance. The sides of a hinge joints provide support but don't form a lock, on their own the curves would still allow a range of motion that the muscles and tendons would need to restrain, not to mention the need to provide variable lateral support on their own when it comes to resisting outside forces, which would be needed for anything that adapted its limbs to fly inside an atmosphere.

Those are pulling on the foot bones aka moving the toes and have nothing to do with stabilizing the ankle joint?

While I am still cautious with how well I'm interpreting the information, "have nothing to do with the ankle joint" is almost certainly false:

QUOTE

Eight modelled ostrich limb muscles also show this pattern: the AMB1, AMB2, IC, ITCa, ITCp, ITM, ITCR and ISF exhibit stabilization function in flexion-extension (Figs. 9 and 10). Weaker evidence for self-stabilization is present for the OM muscle in hip ab/adduction (Fig. 14) and the four ankle flexors in flexion/extension (TCf, TCt, EDL, and FL; Fig. 18), so any self-stabilization properties must be interpreted as being largely restricted to the hip’s flexion-extension function (see also Table 4).

QUOTE

Ankle musculature displays fairly congruent patterns in our model and S.E.A. and B.A.S.’s data (Figs. 18 and 19). The TCf and TCt heads generally have an ankle extensor action, like the EDL muscle group does, albeit with some switches to extensor action with extreme (dorsi)flexion in the B.A.S. dataset (and our TCf). Surprisingly, ankle extensors reveal more variation: our FDL’s ankle extensor moment arm is almost twice as large of that in the S.E.A. and B.A.S. data, showing little change with ankle posture, whereas the B.A.S. dataset exhibited a decreased moment arm with flexion. Our other digital flexor muscles (FPD3, FPD4) and those of S.E.A. display roughly similar values but opposite trends, increasing their moment arms with ankle flexion in our model. Our FL muscle’s extensor moment arm is smaller than those of S.E.A. and B.A.S. The model of B.A.S. had a M. fibularis brevis (FB) muscle (Fig. 18), which is reduced to a ligament in Struthio and thus not included in our model; no studies have data for the ligamentous M. plantaris (Zinoviev, 2006). The extensor moment arms for our gastrocnemius muscles are all identical and fairly constant with ankle flexion, whereas the curves for the data of S.E.A. and B.A.S. increased steadily and tended to be larger (Fig. 19).

Source: https://nmbl.stanford.edu/publications/pdf/...chinson2015.pdf

Not to mention, what's the point on insisting on a joint that wouldn't allow a sauceback to survive a mild kick from the side or to stumble over a rock? You can't reasonably argue against the need to withstand lateral forces and then have it push against air resistance in the same breath, that's absurd.

This post has been edited by Jarlaxle: Feb 3 2023, 06:48 PM

QUOTE (Jarlaxle @ Feb 3 2023, 08:47 PM)

While I am still cautious with how well I'm interpreting the information, "have nothing to do with the ankle joint" is almost certainly false: QUOTE Eight modelled ostrich limb muscles also show this pattern: the AMB1, AMB2, IC, ITCa, ITCp, ITM, ITCR and ISF exhibit stabilization function in flexion-extension (Figs. 9 and 10). Weaker evidence for self-stabilization is present for the OM muscle in hip ab/adduction (Fig. 14) and the four ankle flexors in flexion/extension (TCf, TCt, EDL, and FL; Fig. 18), so any self-stabilization properties must be interpreted as being largely restricted to the hip’s flexion-extension function (see also Table 4). QUOTE Ankle musculature displays fairly congruent patterns in our model and S.E.A. and B.A.S.’s data (Figs. 18 and 19). The TCf and TCt heads generally have an ankle extensor action, like the EDL muscle group does, albeit with some switches to extensor action with extreme (dorsi)flexion in the B.A.S. dataset (and our TCf). Surprisingly, ankle extensors reveal more variation: our FDL’s ankle extensor moment arm is almost twice as large of that in the S.E.A. and B.A.S. data, showing little change with ankle posture, whereas the B.A.S. dataset exhibited a decreased moment arm with flexion. Our other digital flexor muscles (FPD3, FPD4) and those of S.E.A. display roughly similar values but opposite trends, increasing their moment arms with ankle flexion in our model. Our FL muscle’s extensor moment arm is smaller than those of S.E.A. and B.A.S. The model of B.A.S. had a M. fibularis brevis (FB) muscle (Fig. 18), which is reduced to a ligament in Struthio and thus not included in our model; no studies have data for the ligamentous M. plantaris (Zinoviev, 2006). The extensor moment arms for our gastrocnemius muscles are all identical and fairly constant with ankle flexion, whereas the curves for the data of S.E.A. and B.A.S. increased steadily and tended to be larger (Fig. 19). Source: https://nmbl.stanford.edu/publications/pdf/...chinson2015.pdf Not to mention, what's the point on insisting on a joint that wouldn't allow a sauceback to survive a mild kick from the side or to stumble over a rock? You can't reasonably argue against the need to withstand lateral forces and then have it push against air resistance in the same breath, that's absurd.

That first paragraph appears to be saying, in layman's terms, "the evidence that these might stabilize the ankle is very weak, stabilization is probably restricted to the hip region". The hip can move laterally in both birds and saucebacks, and is also what you use to move your leg to catch yourself when you stumble or get kicked from the side.

The second paragraph has nothing to do with lateral motion of the ankle joint.

QUOTE (Disgustedorite @ Feb 4 2023, 03:02 AM)

QUOTE (Jarlaxle @ Feb 3 2023, 08:47 PM) While I am still cautious with how well I'm interpreting the information, "have nothing to do with the ankle joint" is almost certainly false: QUOTE Eight modelled ostrich limb muscles also show this pattern: the AMB1, AMB2, IC, ITCa, ITCp, ITM, ITCR and ISF exhibit stabilization function in flexion-extension (Figs. 9 and 10). Weaker evidence for self-stabilization is present for the OM muscle in hip ab/adduction (Fig. 14) and the four ankle flexors in flexion/extension (TCf, TCt, EDL, and FL; Fig. 18), so any self-stabilization properties must be interpreted as being largely restricted to the hip’s flexion-extension function (see also Table 4). QUOTE Ankle musculature displays fairly congruent patterns in our model and S.E.A. and B.A.S.’s data (Figs. 18 and 19). The TCf and TCt heads generally have an ankle extensor action, like the EDL muscle group does, albeit with some switches to extensor action with extreme (dorsi)flexion in the B.A.S. dataset (and our TCf). Surprisingly, ankle extensors reveal more variation: our FDL’s ankle extensor moment arm is almost twice as large of that in the S.E.A. and B.A.S. data, showing little change with ankle posture, whereas the B.A.S. dataset exhibited a decreased moment arm with flexion. Our other digital flexor muscles (FPD3, FPD4) and those of S.E.A. display roughly similar values but opposite trends, increasing their moment arms with ankle flexion in our model. Our FL muscle’s extensor moment arm is smaller than those of S.E.A. and B.A.S. The model of B.A.S. had a M. fibularis brevis (FB) muscle (Fig. 18), which is reduced to a ligament in Struthio and thus not included in our model; no studies have data for the ligamentous M. plantaris (Zinoviev, 2006). The extensor moment arms for our gastrocnemius muscles are all identical and fairly constant with ankle flexion, whereas the curves for the data of S.E.A. and B.A.S. increased steadily and tended to be larger (Fig. 19). Source: https://nmbl.stanford.edu/publications/pdf/...chinson2015.pdf Not to mention, what's the point on insisting on a joint that wouldn't allow a sauceback to survive a mild kick from the side or to stumble over a rock? You can't reasonably argue against the need to withstand lateral forces and then have it push against air resistance in the same breath, that's absurd. That first paragraph appears to be saying, in layman's terms, "the evidence that these might stabilize the ankle is very weak, stabilization is probably restricted to the hip region". The hip can move laterally in both birds and saucebacks, and is also what you use to move your leg to catch yourself when you stumble or get kicked from the side. The second paragraph has nothing to do with lateralmotion of the ankle joint.

Not quite. The 2nd paragraph looks like its saying that the specific ankle muscles maintain their tension on the ankle throughout the walking stance regardless of pose pulling underneath the ankle from both sides consistently throughout the step, so a slightly more thorough reading of the 1st paragraph is "we do have evidence for stabilization in the knee muscles but we acknowledge that it isn't as strong or clear cut as the evidance for stabilization from the hip muscles".

And before you conclude that gives you enough leeway to leave the biat ankle without any muscles for withstanding lateral forces, that's still not viable once you are using those limbs to withstand air resistance during flight.

This post has been edited by Jarlaxle: Feb 3 2023, 08:04 PM

You keep missing the mark by trying to shoot down the visorbill without shooting down biats a as whole in the process, and at this point you've exhausted me enough to try and help you: If for some reason you really really really really wanted to do just that just for the sake of it while still maintaining a semblance of plausibility (though not enough to count plausibility as a reasonable cause for the decision), I would suggest making the wing equivalent of an alligator mouth, putting all the lateral force on the top and nearly non at the bottom.